The status for Amoya brevirostris is long being uncertain, partly due to lack of coloration information. It seems that the holotype inspected by Gther( Gobius brevirostris Gther, BMNH 2005.10.3.1) had lost its coloration when it reached the researcher, because in the original description, the author only mentioned: Uniform brownish-olive(in spirits); the second dorsal with series of brown dots; caudal, anal, and ventral with the margins blackish..
Such incomplete description in coloration is not sufficient to identify this sp. effectively, it’s easy to confuse it with sibling sp.. Unfortunately, no known effort has been made to find out the actual color of this fish in the last 80 years. Many books, keys still use more or less the same description of coloration of Gther’s. And that’s why we have much trouble looking up this colorful creature in our books when we first found it, because they all say that the fish is “plain in color, with a obscure thick dark line through the lateral”.
Instead of Ctenogobius brevirostris in our key, we accidentally followed the key to Oligolepis moloanus at first. When I soon found out the valid name is Amoya moloanus, and found a colored picture of it. At the first sight, I almost believe we’re right about it. Not just because they have almost the same body outline, but also because both our specimen and A. moloanus has the eye-catching 8 shining spots along the body side. And, interestingly, in spite of the shape, the color pattern of the spots are very similar – metalic blue-green with red margin. The only difference I noticed was that A. moloanus has a clear black line from below eye to the upper mouth base. I asked Helen Larson about it, she doesn’t know the exact sp., but she did think the specimen we’d got was very close to A. moloanus. Then she forwarded my email to Zeehan, who’s revising Acentrogobius et Amoya.
During those days, I also looked up the internet for goby photos, and again accidentally came to a website that shows the type specimen of Ctenogobius chusanensis from China. It looks like our specimen too! I at once sensed they should be very close related. Of course, just a guess, before examing the specimen or have look into any literature, I could not decide.
Until recently, I read a paper about the name revision for C. chusanensis (Zhao Shenglong et Zhong Junsheng) . The author suggested to move this sp. from Ctenogobius from Acentrogobius after comparing it to Amoya brevirostris and Acentrogobius moloanus(syn. of Amoya moloanus). It proves that I’m not the only person who notices the similarities between these 3 spp.. However, other authors have already moved both A. chusanensis and A. moloanus into Amoya. With our description of coloration for A. brevirostris, this speciei status should be sure. It’s very close related to Amoya chusanensis, with similar coloration, and sex differences. I even doubt they could be synonyms, or assigned as subspecies. I’m not sure about A. moloanus, but it seems that this sp. is further away than the relationship between the previous two spp. according to their distribution and coloration.
Finally, I want to say that the countable features may not be very reliable to identify the spp. in this genus. Usually, the coloration works better if a fresh specimen is available.